1. Technical Field
The present invention relates to a projector, and, more particularly to a technique for a projector that displays an image using a laser beam.
2. Related Art
In recent years, there is proposed a technique for using a laser beam source as a light source device for a projector. The laser beam source is developed as a light source for a projector according to an increase in power and an increase in colors. Compared with a UHP lamp used in the past as a light source for a projector, the laser beam source has advantages that, besides being small in size, for example, color reproducibility is high, instantaneous lighting is made possible, the durable life is long. It is possible to display a bright image by using the laser beam source with high power. On the other hand, it is necessary to take measures for preventing deficiencies that are likely to be caused by laser beams such as the influence of a laser beam affecting the eyes when the laser beam directly enters the eyes. For example, JP-A-2003-269915 proposes a technique for a three-dimensional monitoring device that makes it possible to highly accurately detect an object that enters a three-dimensional space. By applying such a technique to a projector and taking measures for, for example, detecting an object that enters a monitoring region to which a laser beam travels and stopping the output of the laser beam, it is possible to prevent the deficiencies that are likely to be caused by laser beams.
The projector is assumed to be used in all kinds of situations. Not only a person but also, for example, an object other than a person may enter the monitoring region. A monitoring image may change from an initial state for some cause, for example, a change in brightness in the monitoring region. Therefore, it is possible that the output of video light is frequently stopped even when it is unnecessary to stop the output. When the unnecessary stop of the output is frequency performed, comfortable video entertainment is hindered. If it is necessary to perform an arithmetic operation using an extremely large number of parameters in order to highly accurately detect that a person enters the monitoring region, the structure for monitoring is complicated. In this way, the technique in the past causes a problem that it is difficult to realize, with a simple configuration, both reduction in deficiencies that are likely to be caused by light and comfortable video entertainment.